Jig



APII 1950 v V w. HAYESl 2,502,840

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JIG

Filed March 6, 1945 '7 Sheets-Sheet 5 INVENTOR Wm L /E HA VES,

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April 4, 1950 w. HAYES 2,502,840

JIG

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Patented Apr. 4, 1950 UNITED JIG Willie Hayes, Pratt City, Ala.,assignor to Tennessee Coal, Iron and Railroad Company, a corporation ofAlabama Application March 6, 1945, Serial No. 581,269

2 Claims.

heavier concentrate is maintained substantially constant in the cell ofthe jig, whereby overloading of the jig is prevented.

A still further object of the invention is the provision of a jig whichinsures the delivery of separated material of constant quality.

The above and further objects of the invention will become more apparentin the following description.

The jig of the present invention is useful in the separation of mineralsof different specic gravities as, for instance, metal-bearing ores andcoal from rock. For the sake of simplicity, the invention will bedescribed in connection with its use in the washing of coal, that is,the separation of coal from various impurities such as rock, slate, andthe like, but it is to be understood that the invention nds advantagesin the separation of other materials, as above indicated.

The invention relates to jigs of the type wherein the material to beseparated is fed onto a screen in a bath of liquid, and is subjected torapidly recurring impulses of the liquid through the screen which tendto lift the material and to stratify it in accordance with its specicgravity. The finer, heavier, material passes through the screen and isdrawn off from the bottom of the jig as a sludge. The heavier materialretained on the screen which, in the case of the washing of coal, iscomposed of slate and other rocks, is removed from the screen through arock valve, whereas the lighter material passes ovel` a barrier at theend of the cell. Such type of jig, which is well known, is disclosed inthe Elmore patents, Nos. 1,077,876 and 1,327,537.

It has been recognized that for the vmost enicient operation of jigs ofthis type it is desirable to retain on the screenof the cell as uniforma depth of concentrates as possible, so that the action of the pulsatingliquid upward through the screen and through such bed of concentrateswill be uniform. In prior art designs it has been attempted to maintainsuch uniform depth of concentrates on the cell screen either by manuallycontrolling the rate of feed of material into the cell and the rate offeed of heavy concentrates, which is rock in a coal washing jig, fromthe cell, o1' by manually controlling the lrate at which material is fedinto the cell and automatically controlling the rate of discharge ofrock from the cell in accordance with the depth of the rock bed on thescreen. Such latter arrangement is shown in Elmore Patent No. 997,609.

Such methods of controlling the cell have worked fairly satisfactorilyWhere the composition of the material fed into the cell has stayedwithin fairly close limits. Such a condition is met, for instance, whencoal mined from a vein of substantial thickness is hand-loaded at themine face, since such hand loading excludes, to a large extent, piecesof rock and slate. Where, however, the composition of the materialvaries considerably and changes in the composition of the material beingfed occur very rapidly, such methods of control are not satisfactory dueto the operators inability to appreciate the need for a change in rateof in-feed before the harm has been done. It has been found that wherecoal is mined from a relatively thin vein and the coal is mechanicallyloaded at the mine face, such coal is apt to contain large amounts ofrock and the rock content is apt to vary considerably from time to time.If, because of such rapid change in composition, the depth of rock inthe cell becomes so high that the capacity of the rock valve isexceeded, the cell no longer separates completely the lighter from theheavier materials and certain amounts of such heavier materials arewashed over with the lighter separated portions;

The present invention provides a jig which overcomes these `difficultiesand produces a product of uniform quality'regardless of the rock contentof the in-fed material or of the rapidity of change of such content.Such objects are accomplished by the provision ofmeans automaticallycontrolling the height'of the rock bed in the jig cell by varying therate of in-feed of the coal, thereby avoiding the possibility ofoverloading the jig. At the Sametime, however, the jig is kept workingat full capacity and therefore at its maximum eiciency.

The invention will be more readily understood by reference to theaccompanying drawings, in which:

Figure 1 is a view in side elevation of a coal Washing jig made inaccordance with the present invention;

Figure 2 is a View in plan of the jig shown in Figure 1;

Figure 3 is a View in transverse cross-section 3 through the first cellof the coal washing jig, such section being taken along the line II-llof Figure 2;

Figure 4 is a view in longitudinal cross-section of the in-feeding endof the jig;

Figure 5 is a detail view of the float-operated rock level indicatingswitch;

Figure 6 is a detail View of the door-positioning limit switch;

Figure 6A is a View in end elevation of a portion 0f the door-operatingmechanism;

Figure 6B is a view in section through such portion of thedoor-operating mechanism, the section being taken along the line VIB inFigure 6A;

Figure '7 is an enlarged view of one portion of the door-positioninglimit switch;

Figure 8 is an enlarged View of another portion of the door-positioninglimit switch;

Figure 9 is a schematic view of a portion of the rock discharge valveoperation mechanism: and

Figure 10 is a schematic wiring diagram of the electrical control forjig of the present invention.

The jig illustrated in the drawings consists of three cells seriallyarranged. The first cell. designated by the reference character 2, isfed with the raw coal to be washed, and discharges the lighter of theseparated materials into the second cell 4 which in turn discharges thelighter of the materials separated in it into the third and final cell6. Each of the cells is provided at the sides thereof, as shown inFigure 3, with four eccentrically actuated plungers 8 which reciprocatein vertical plunger chambers lil. plungers impart a series of surges orvibrations to the water with which the cell and the plunger chambers areiilled, whereby the water intermittently rises and falls through thescreen oor of each cell and through the bed of material supported bysuch screen. The screen in the first cell is designated by the characterI2. Such vertical motion of the water in the cell accomplishes thewashing out of the line heavy particles from the material, whichparticles fall through the screen into the bottom or hutch Il! of thecell, from which they are discharged through hutch valve l5.

`Plungers 8 are driven by means of a horizontal drive shaft i3 which inturn is driven by a motor through the medium of a motor pinionrrleshinfr4 with the large gear on the end of shaft la, as shown inFigure 2. Bevel pinions 2i! and ZI are affixed to shaft I8 in positionto mesh with pinions 22 and 23, respectively, on the longitidinaleccentric shafts 24 and 26, respectively, above plunger' chambers IE?.Eccentrics on shafts 'M and 2G are connected to plungers 8 and providefor the vertical reciprocation thereof.

The rapidly repeated surges of the water upwardly through the bed of thematerial on the screen straties the material into the lower, heavier,layer of rock R, and the upper lighter, more buoyant, layer of coal C,as shown in Figure Il. The feed of material into the cell at theleft-hand end thereof tends to make such bed of greater depth at suchpoint, the bed levelling out as it travels gradually to the right. rl"herock layer R remains in contact with the screen and gradually travelsinto the rock valve pocket 32. whence it is fed into the generallystar-shaped rotary rock valve 34 which discharges it into chute 35leading to a refuse flume, when each pocket in the valve reaches itslower position. The lighter layer of coal C, on the other hand, is

` 4 progressively washed up and over end barrier 28 at the right-handend of the cell and down inclined chute 3D into the succeeding cell il.It is to be understood that separation 0f the coal from the rock is notcomplete in the nrst cell, which explains the use of the two subsequentcells. but that usually some rock is washed over the barrier into thesecond cell, as shown in Figure 4 of the drawings. With the 3-cell jigas shown, the material discharged from the rock valves of the rst twocells is refuse, whereas that discharged from the rock valve 0f thethird cell 5 is lowquality coal employed as boiler coal; the lightermaterial finally discharged from the third cell is i. high-qualitywashed coal which may be employed, for instance, in the making of coke.

t will be apparent from the above that if the rock layer R in the firstcell has a thickness in excess of that desired and consequently adischarge rate materially in excess of theI capacity of the rotary rockvalve of the rst cell, large quantities of rock will be washed overbarrier 28 of the first cell, into the second cell. and that as aconsequence, the second cell will be overburdened, and the dischargefrom the rockvalve of the` third cell may have an unduly high rockcontent. There will also be the further possibility oi the presence ofsome rock in the lighter diccharged material from the third cell.

The rock valves 34 of the iirst cell, as well those of the succeedingtwo cells, are driven by ratchet drive devices indicated generally at138 in Figure Such ratchet drives are driven bv means of a verticalshaft Ml shown in Figure 2. which is driven olf shaft I8, shaft 4I] inturn driving a lower transverse shaft 42 to one end of which is aflixeda crank 44. Pitman l5 connected to crank 44 effects the oscillation ofratchet drive 38 of the rst cell, and pitmans M, which extend betweenthe ratchet drive meer: of the rst, second, and third cells` drive therock valves of the two latter cells. Adjustment of the, rate at whichthe rock valves are driven` is .accomplished by means of adjustingwheels 53 bv which the length of the ratchet arm of the particularratchet drive of which it is a part mai1 be varied.

In accordance with the present invention. the first cell 2 of the jig isprovided at the left, as

shown in Figures 1 and 2, with a coal bin 5l) into which the coal to bewashed is fed. The lower portion of the coal bin is provided with apowerdriven revolvingr feeder 52 equipped with radial projections whichpick the coal up and discharge it into the first cell. Coal thusdischarged impinges upon angular deecting plate 54 positioned in thefirst cell, as shown. Control of the rate at which coal is fed from thebin to the rotary feeder is eifected by means of a vertically slidablebin closing gate 56, which may be adjusted by means of racks 58 affixedthereto, such racks meshing with pinions 60 on transverse shaft 62.Rotation of the shaft and consequent adjustment of the bin gate isaccomplished by means of handwheel G4. The control of the rate of feedaccomplished by gate 56 is in the nature of a rough adjustment, and oncemade, gate 56 may be left in the desired position.

Control of the rate of feed to the first cell within the limitsnecessary to effect automatic feedingv of the jig is accomplished bymeans of door 5S cooperating with the revolving feeder 52. said doorbeing mounted, as shown, on a swinging frame pivoted about a shaft 52,whereby the free space between the revolving feeder and the lower end ofthe door may be varied. Such swinging of frame 68 is effected, in themodification `of the apparatus shown, by means of a gear motor lItmounted on a platform supported on beams above the first cell 2. Drivenshaft 'I2 lof the gear motor is connected to a vertical screw "I3journaled in lower bearing 'I4 and in an upper bearing 'I6 on top of thedoor-positioning limit switch box TI. Screw 'I3 is composed of a lowerportion 'I8 of substantial diameter, which effects the adjustment offrame 60, and an upper portion 80, shown in Figure 6, of somewhatsmaller diameter. Nut 82 on lower screw portion 'I8 is provided withtransverse arms 84 which slide in vertical guideways 86. The swingingframe 68 is provided with a door-operating arm 88 having an outer forkedend, the arms of such fork having slots 90 therein for the reception ofarms 84 of nut 82. Such structure makes possible the lowering or raisingof the door 56, as required, by gear motor l0, such motor, in turn,turning screw 18, thereby raising or lowering arm 88 depending upon thedirection of rotation of the motor.

The door operating mechanism is automatically operated in accordancewith the height of the -v rock bed R in the first cell of the jig by thefollowing mechanism acting in conjunction with the door-positioninglimit switch device in switch box TI. A iioat III, which rests uponthetop of the rock bed R and is preferably of streamlined shape tofacilitate the iiow of material past it, is mounted on the bottom end offloat rod I I2. `Such float rod is positioned and guided for verticalmovement by means of guide rollers H3, which are supported over the cellby means not shown. The float is held in contact with the top ,of therock bed at a location where the bed tends to be level, with the desiredamount of pressure by means of counterweights H5 held in counterweightholder IM at the upper end of the float rod. The rock level indicatingswitch, which is actuated by iioat rod H2, is shown in detail in Figure5. Switch box H0, through the bottom and top of which float rod H2extends, has mounted thereon on one side of the float rod an elongatedbus bar H8 and on the other side of the float rod an insulating plate II9 which mounts the contacts labeled FL3, FL2, FLI, FRI, FR2, and FVC.The first iive of these contacts are, as shown, of short extent, whereasthe lowest, FVC, is of considerable length. The upper surfaces of suchcontacts are substantially flush with the top surface of the insulator II9, to enable the contact arm I I1 which is mounted upon iioat rod H2 byan insulating bushing H'I, to ride freely thereover while still makingcontact therewith as the iioat rod rises and falls. Vertical adjust mentof arm I I 'I with respect to the float rod may be made by means of theset screw H8 in the insulating bushing I'I' upon which arm II'I ismounted. It will be apparent that such switch structure provides a meanswhereby the circuit is closed btween bus bar H8 and any one of thevarious contacts FL3, etc., only when contact arm I I1 touches one ofthe contacts.

The structure of the door-positioning limit switch mechanism in switchbox 'I'I is shown more fully in Figure 6. As there shown, the switch isin the neutral position, corresponding to the normal or neutral positionof the rock level contact arm I I'I shown in Figure 5. Theswitchoperating arm 94 is threadedly engaged with the screw 80 so as tobe raised and lowered in accordance with the motion of door-operatingnut 82. Rotation of arm is prevented by the provision of a rearwardlydirected arm 96 attached thereto, said latter arm having a slidingengagement with the vertically fixed guide rod 98 positicned in theswitch box.` Arm 04 is provided with a series of vertically-extendingswitch-operating fingers |00, IOI, |02, |03 and |04, said fingers beingadjustable vertically of arm 94 and retained therein by means of setscrews, as shown. Each of the switch-operating fingers is provided withan inclined forward end, as more clearly shown in Figures '7 and 8, forthe operation of the microswitches.

The switch 2D, shown in Figure 7, is typical of switches ID, 2D, and 3D,whereas switch IU, shown in Figure 8, is typical of switches IU and 2U.Switch 2D has a switch element |05 which is held in raisedcircuit-breaking condition by a spring member |05 when switch-operatingfinger |0| is in the lower position shown by the dotted line. When suchswitch member is advanced vertically, however, as shown in full lines,it oontacts roller I 01 and depresses the switch member in order tocomplete the electric circuit through the switch.

The switch IU, however, which is provided with switch element |08, is ofsuch construction that it is closedwhen the switch-operating finger |03is positioned in the lower full line position shown. When member |03 isadvanced upwardly to the dotted line position, it engages roller IIO onthe end of spring |09, thereby depressing the switching element andbreaking the electric circuit through the switch.

The door positioning limit switch functions, as will be more clearlyapparent in considering the wiring diagram in Figure l0, to stopoperation of the door adjusting motor 'I0 when the door has reached apredetermined position depending on the position of the float III. Thedoor-positioning limit switch accomplishes this by breaking itsparticular contact through which the control circuit energized byclosing of the float contact is completed, when the door reaches therequired position. It will be obvious from a consideration of Figure 6that limit switch ID opens at the first door position below normal, andthat limit switches 2D and 3D operate similarly at the second and thirdpositions, respectively, below normal. Limit switches IU and 2U open atthe first and second positions, respectively, above normal. Each limitswitch opens and remains open as long as the door is at or past thatparticular position away from the normal position of the door.

The operation of the automatically controlled feeding device for the jigthus far described will be more fully understood by reference to theschematic wiring diagram shown in Figure 10, in which thedoor-positioning limit switches are all shown closed, and the rock levelcontacts are all shown open, as they are when the rock level is ofnormal height and the door is in its normal position. Thedoor-positioning motor 'I0 is caused to raise or lower the door wherebythe mechanism tends to hold the rock level in the first cell such thatthev contact arm IIi normally lies between contacts FLI and FRI. Suchposition, which is called the normal or neutral position, is attainedwhen the height of the rock bed in the cell is at its optimum value.When arm I I1 is within such range and touching neither contact FLI norFRI,

motor I0 is at rest and the door is held in xed position. If, however,the height of the rock bed should rise sufficiently to bring contact armH1 into position to touch contact FLI, motor 'I0 is actuated tolower'the door to correct such condi- 7 tion' and to bring the' heightof the rock bed back to its normal value. VIf the rock bed level risesstill further, however, switch FL2 operates to cause motor 10 to lowerthe door still further. Switch FL3 is effective, when the rock levelrises suflciently to cause it t complete the circuit, to operate motorto close the door still further to correct the condition. If the levelof the rock bed falls, on the other hand, so as to cause contact arm |11to touch contact FRI, motor 10 is caused to rotate in such direction asto raise the door to admit more coal, and thus to correct the conditionand bring the rock level back to normal. Upon further fall of the rockbed level, however, should such occur, switch FR2 is operated to raisethe door still further. If the rock level should, in spite of this, fallto such point that arm ||1 touches contact FVC, the ratchet feedmechanism 38 for the rst cell is caused to be ineffective, by a meanssubsequently to be described, whereby rotation of the rock valve 34 isstopped. It will be 'apparent that each of the various switches FLL PL2,FL3, FRA, FB2, and FVC closes the circuit, thereby operating motor 10,only when contact arm I |1 touches that particular contact.

The motor 10 is supplied from an appropriate three-phase alternatingcurrent source to which are connected the three lead wires LI, L2, andL3. Such source of current, besides supplying motor 10, is employed toenergize the six relays, IL, 2L, 3L, R, 2R, and VC, corresponding to thesix contacts, FLL etc., and also to energize the two operating coils ofthe reversing contactor RC. The reversing contactor RC is a conventionaldevice having two operating coils and |91 which, when operatedselectively, establish contacts for operating the motor in oppositedirections. The contactor is of such construction that neither of suchoperating coils is energized when the contactor is in neutral position,and the circuit to the motor is broken and the motor is stopped.

The wiring diagram will be more readily understood by tracing thecircuits therethrough which are utilized when the rock bed in the rstcell of the jig rises progressively from the normal level so as to closeswitches FLI, FLZ, and FL3 successively, and also the circuits which areenergized when the rock bed level falls from the normal level so as toclose switches FRI, FRZ, and FVC, successively.

First, assuming that the rock bed level has risen from normal to a pointsufficiently to allow contact arm l i1 to touch Contact FLI motor 10 isactuated in a direction to lower the door, thereby decreasing the rateof feed of coal into the jig.

Such actuation is accomplished by the connection oi one side of theactuating coil |26 of relay IL to line L| through wire |20, wire |22,closed switch FLI, and wire |23, and by the connection of the other sideof coil |26 to line L3 through wires I3| and |30, closed limit switchID, and wire |28.

Energization oi' relay coil |26 closes its contacts |32 and |34, therebyenergizing coil |36 of the reversing contactor RC in the followingmanner:

Current travels from lead L3 through wires |38, |39, 40, |42, and |44 toone side of coil |36, and from lead Ll through wires |20, |22, and |49,contact |34, wire |5I, contact 204, and wire |52, to the other side ofcoil |36. Thereupon the reversing contactor RC is thrown to close itscontacts |54, |50, and |58 and to open normally closed Contact |00. Thewires 'I'|, T2, and T3 of motor 10 are then connected to lines L3, L2,and LI, respectively, as follows:

From lead LI current flows to wire |62, wire |64, through contact |58,to wires |66 and |61, and thence to wire T3 of the motor. Current flowsfrom lead L2 to wires |68, wire |69, through contact |56, to wire |10and thence to wire T2 of the motor. Current flows from lead L3 to wire|38, wire |39, through contact |54 and wires |12 and |14 to line Tl ofthe motor. The motor operates to lower the door until operating finger|02 of the door-positioning limit switch is lowered suiciently to allowthe opening of switch |D. This breaks the circuit to relay IL, the coil|36 of the reversing contactor is deenergized, the reversing contactorgoes back to its neutral position, and the motor 10 stops.

If the rock bed level in the first cell of the jig continues to rise,contact arm ||1 passes contact FLI, and if the rise continues, the armtouches contact FL2. When such contact is made, relay 2L is energized asfollows:

Current ows from lead LI through wires |20 and |22, contact FLZ and wire|16, to one side of the operating coil |11 of relay 2L. Current flowsfrom lead L3 through wire |3|, wire |30, closed limit switch 2D, andwire |18, to the other side of coil |11.

Energization oi relay-operating coil |11 closes its contacts and |82,thereby energizing coil |30 of the reversing contactor in the followingmanner:

Current flows from lead L| through wires |20, |22, |83, |8I, contact|82, and wires |50, |5|, switch 204, and wire |52 to one side of coil|36. The other side of such coil is supplied from lead L3 through wires|38, |39, |40, |42, and |44. Operating coil |36 then throws thereversing contactor and operates motor 10 in the same direction asbefore, to lower the gate. Such operation of the motor continues untillimit switch 2D is opened by the fall of operating nger I 0|, at whichtime the relay 2L is deenergized, the reversing contactor returns toneutral, and the motor stops.

The same sequence of operations follows, should the rock bed level incell 2 rise sufficiently for contact arrn ||1 to touch contact FL3. Insuch case, operating coil 2|2 of relay 3L is energized with current fromlead Ll through wires |20, |22, closed switch FL3, and wire 2|0 and fromlead L3 through wires |3|, |30, closed limit switch 3D, and wire 2|4.

Upon energization of coil 2 |2 of relay 3L, contacts 216 and 2|8 of thelatter are closed, and operating coil |33 of the reversing contactor isenergized as follows:

Current flows from lead L| through wires |20, |22, |83, IBI, |84, |85,contact 2|8, wires 220, |50, |5|, switch 204, and wire |52 to one sideof coil |36. The other side oi such coil is supplied with current fromlead L3 through wires |38, |39, |40, |42, and |44. Coil |36 againoperates the reversing contactor to establish connections so that motor10 rotates in such direction as to lower the door, and the motor isstopped upon the opening of limit switch 3D and the consequentdeenergization of relay 3L.

Assuming now that the rock bed level has been normal but has fallen to alevel such that contact arm ||1 touches contact FRI, motor 10 isoperated in the opposite direction, to raise the door, thereby to admitcoal at a faster rate and correct such condition. In such case operatingcoil 222 of relay IR is energized as follows:

Current ows from lead LI through wires |20 and |22 through closed switchFR|, and through Wire |88 to one side of coil 222. The other side ofsuch coil receives current from lead L3 through wires |3|, |30, closedlimit switch |U, and wire |89.

Energization of coil 222 closes contacts |90 and |92 of relay IR,thereby energizing operating coil |91 of the reversing contactor RC.Coil |91 is energized as follows;

Current flows from lead L| through wires |20 and |22, closed contactsFRI, wire |88, contact |90, and wires 224, contact |92, wire |94, switch|60 and wire |96, to one side of coil |91. The other side of such coilreceives current from lead L3 through wires |38, |39, |40 and |42.Energization of operating coil |91 causes the reversing contactor RC tobe thrown in such direction as to close switches |98, 200, and 202 andto open normally closed switch 204. Leads LI, L2, and L3 will now-beconnected to motor Wires Tl, T2, and T3, respectively, thereby operatingthe motor in the reverse direction and causing the door to rise.Connection of the motor to the current source leads is effected asfollows:

Current flows from lead L| through wire |62, switch 202, and wire |14 towire Tl. Current flows from lead L2 through wire |68, switch 200, andwires |2| and |10, to wire T2, and current ows from lead L3 through wire|38, switch |98, and wires |25, |66, and |61 to wire T3. Rotation of themotor 10 to effect opening of the door continues as long as switch FRland limit switch IU are closed, and stops when either opens. Normallyactuation of the motor is stopped by the opening of limit switch IU bythe rise of operating finger |03.

If the rock level in the first cell 2 continues to fall, however,contact |1 will touch contact FB2 to energize relay 2R and again operatemotor 10 in such direction as to raise the door. When this occurs,operating coil 228 of relay 2R is energized by means of current flowingfrom lead Ll, through wires |20, |22, closed switch FRZ, and wire 226 toone side of coil 228. The other side of such coil receives current fromlead L3 through wires |3|, |30, closed limit switch 2U, and wire 229.

Energization of coil 228 of relay 2R causes closing of its contacts 230and 234, thereby energizing operating coil |91 of the reversingcontactor as follows:

Current flows from line LI through wires |20 and |22, closed contactsFR2, wires 226, 230, and 232, contact 234, wires 236 and |94, contact|60 and wire |96, to one side of coil |91. The other side of such coilreceives current from lead L3 through wires |38, |39, |40, and |42.Motor 10 is thus operated again in such direction as to raise the door,and operates until either switch FRZ or limit switch 2U is broken.

If the rock level in the cell should continue to fall, contact arm ||1will touch contact FVC. The closing of switch FVC operates relay VC inthe following manner:

Current flows from lead LI through wires |20, |22, closed switch FVC,and wire 206 to one side of the operating coil 238 of the relay VC. Theother side of such coil is supplied with current from lead L3 throughwires |3|, 240, and 208. Energization of coil 238 of the relay closesits contact 242, thereby energizing the pawllifting solenoid 248 of theratchet feeding device subsequently to be described, which is suppliedwith current from a separate current source,

l0 L4 and L5. Current then flows in the pawllifting solenoid circuitfrom line L4 through wire 244, contact 242, Wire 246, through solenoidcoil 248, and back to lead L5.

Energization of solenoid coil 248 lifts the driving pawl of the ratchetmechanism shown in Figure 9 through which the rock valve 34 of the rstcell is driven. Thereupon discharge of rock from the first cell ceases,and remains stopped so long as switch FVG is closed, thereby allowingthe level of the rock in the cell to build up. As shown in Figure 9, theratchet drive mechanism for the rock valve consists of an arm 250pivoted about the rock valve shaft 252 and operated by pitman 46, abovedescribed. Drive pawl 256, pivoted as shown on arm 250, coacts withratchet wheel 254 aflixed to the valve shaft in such a manner as tocause intermittent rotation of the valve upon oscillation of arm 250. Toprevent turning of the ratchet wheel 254 in a reverse direction, thereis provided a springpressed holding pawl 258 attached as shown to aprojection 260 on the side of the first cell near the location of therock valve.

Energization of solenoid 248, which is attached to the upper end of arm250 by a clamping meansn shown generally at 262, attracts the armature284 attached to the upper surface of pawl 256 thereby pulling the pawlfree of the ratchet teeth on ratchet wheel 254 and stopping rotation ofthe rock yalve.

The apparatus of the present invention above described thereforeautomatically insures the maintenance of the rock bed level of the firstcell within such limits as to insure the optimumA operation of the firstcell of the jig, and pre# vents the undue contamination of the lightermaterial carried over from the iirst cell with rock or other heaviermaterial which Would occur if such rock bed should rise to anundesirably high level. Thus the two latter cells may continue theseparation of the material in the most efficient manner. The apparatusis automatic in its operation, and functions to its fullest capacitywhile producing coal of uniformquality, regardless of the amount orrapidity of change of the rock content in the raw infed material.

It is to be understood that the apparatus of the present invention iscapable of numerous variations obvious to one skilled in the art, andthat its scope is to be defined by theappended claims.

Iclaim:

1. A jig for separating materials of differing specific gravitycomprising a cell adapted to contain liquid, mechanism for feeding solidmaterials to said cell and including a gate which has a plurality ofpositions of adjustment, pulsing mechanism 'for stratifying solidmaterials in said cell according to their specific gravities, upper andlower discharges for removing materials from the upper and lower stratarespectively, and control means for adjusting said gate by predeterminedincrements to its different positions of adjustment in accordance Withincremental changes in the stratication level, said control meansincluding a oat adapted to remain at the stratication level, areversible elec- 'said circuits having normally closed limit switchescorresponding with the different positions of adjustment of said gate,said mechanical linkage opening the limit switch in the energizingcircuit when said gate reaches a predetermined position of adjustmentcorresponding with the stratiiication level of the particular set ofcontacts which are closed by said oat, said gate thus remainingstationary until a change in the quality of the feed changes thestratification level by an incremental distance of a magnitude suicientto close a different set of said contacts.

2. A jig for separating materials of differing specic gravity comprisinga cell adapted to contain liquid, mechanism for feeding solid materialsto said cell and including a gate which has a normal opening but isadjustable by xed increments for varying the feed rate, pulsing mechanism for stratifying solid materials in said cell according to theirspecific gravities, upper and lower discharges for removing materialsfrom the upper and lower strata respectively, and control means forregulating the opening of said gate and thereby varying the feed rate byfixed increments in accordance with incremental changes in thestratication level, said control means including a reversible electricmotor, a linkage operatively connecting said motor and said gate, afloat within said cell adapted to remain at the stratication level andhaving a neutral position, an electric circuit for operating said motorto decrease the gate opening tok less than its normal opening and havinga set of contacts which close as said oat rises a xed distance above itsneutral position, an electric circuit for operating said motor in theopposite direction to increase the gate opening to more than its normalopening and having a set of contacts which close as said oat sinks afixed distance below its neutral position, a limit switch in the rstcircuit which is closed when said gate is at its normal opening andopened by said linkage when said gate has closed an incremental distancetherefrom, and a limit switch in the second circuit which is closed whensaid gate is at its normal opening and opened by said linkage when saidgate has opened an incremental distance therefrom, said limit switchesautomatically closing as said gate approaches its normal opening, themotor circuits remaining open and the gate stationary after each gatemovement until the quality of the feed changes sufdciently to change thestratication level by a full increment.

WILLIE HAYES.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,294,757 Bloomeld Feb. 18, 19191,294,864 Bloomeld Feb. 18, 1919 1,345,060 Benson Jan. 29, 19201,619,807 Bloomfield Mar, 8, 1927 2,001,331 Peale May 14, 1935 2,132,755Nichols Oct. 11, 1938 2,270,696 Brentz Jan. 20, 1942 2,272,188 DanielsonFeb. l0, 1942 2,299,959 Brentz Oct. 27, 1942

